Multi Site Shopping cart

I am after the following solution, does anyone know of any cart that can achieve this?

same domain name
one installation / database
shared checkout

domain.com/sporting goods
domain.com/baby goods

I need to display different categories and products depending on which section your are in. But both share the same cart.

One domain name, two dirs or subdomains.
One admin, in admin setup 2nd shop (like opencart, which is way to buggy to use)
Select which cats and products to show on each site
Select which info pages and blocks to show on each site
Customer can switch between the 2 sites during shopping then checkout on either, cart is shared.